The routine transit time for barium through the GI tract is typically ____
30-90 min
Define cerebral blood volume (CBV).
quantity of blood (mL) contained within a 100-g volume of brain tissue
What are the normal ranges for Glomerual Filtration Rate (GFR)?
men= 70
women= 60
Define Feldkamp-Davis-Kress (FDK) algorithm.
cone beam correction used to correct potential x-ray scatter errors on MSCT systems
What is the normal range for cerebral blood flow (CBF) in gray matter?
50-60 mL/100g/min
Define convolution
mathematical filtration used by the CT system to remove blurring artifacts during the back-projection method of image reconstruction.
Define Agatston Score
quantification of volume and density of calcium in the coronary arteries, used to indicate a patient's risk of suffering a cardiac event.
What is the CT Dose Index (CTDI)?
approximate measure of the radiation dose received in a single CT section or slice.
Define edge gradient.
streak artifact that occurs at the interface between a high-density object (example: surgical clips) and the lower-attenuation material surrounding it (example: liver)
What is the normal range for cerebral blood volume?
4-5 mL/100g
Define uticaria.
hives.
Define cerebral blood flow (CBF).
quantity of blood (mL) that moves through 100g of brain tissue each minute.
Cranial nerve #8 is called the ____.
Vestubulocochlear
Define Slice Sensitivity Profile (SSP).
represents degree of broadening that occurs along the z-axis during volumetric data acquistion
what does window width control?
contrast
Define full width at half maximum (FWHM).
midpoint of a SSP where the effective section with is determined
Define contrast resolution.
ability to detect objects with a small difference in linear attenuation.
Define ray.
portion of the x-ray beam that falls on a single detector.
what does window level control?
brightness (density)
Define fomite.
object that has been contaminated by infectious organisms or microbes
Define syndesmosis.
the articulation between the distal tibia and fibula.
what is the major controlling factor of exam quality for a coronary CTA?
patients heart rate.
what are the branches of the left coronary artery?
anterior descending and circumflex arteries.
what are the types of iterative methods of reconstruction?
simultaneous
ray-by-ray
point-by-point
define epidural hematoma
hematoma between the skull and outer most meningeal covering of the brain
what is used in CT to measure mineral content of bone?
quantitative CT
what area(s) of the brain does not enhance after IV contrast?
posterior horn of the lateral ventricles
what is the hall mark CT finding for focal nodular hyperplasia of the liver?
central scar that remains hypo dense after initial contrast administration.
define contre-coup
brain injury on the opposite side of traumatic impact.
areas of calcium identified must demonstrate relative attenuation values greater than ____.
130 HU
why should you angle the gantry 15 degrees superior to the IOML during a head CT?
to reduce radiation dose to the orbits.
what is the ideal heart rate for a CTA chest?
65-70 bpm
what is the average density of a benign solitary pulmonary nodule?
165-200 HU
what factor(s) does spatial resolution rely on?
focal spot size
detector size and spacing
FOV
pixel size
detector sampling rate
Colonography images are best desplayed in a ____ window setting.
wide (lung) type
the stanford type __ dissecting aneurysms affect the descending aorta.
B
Which of these does not commonly become calcified?
a.) thalamus
b.) pineal gland
c.) choroid plexus
Thalamus
each iliac artery bifurcates into the internal and external iliac arteries at the level of ____
L5-S1
stanford type A dissecting aneurysms affect the ____ aorta
ascending
the aorta bifurcates into the left and right common iliac arteries at ____
L4
dual phase imaging with arterial and venous phase is used to evaluate ____
mesenteric vasculature
glioma is a tumor of the ____
brain
CTA of the brain should have a delay of ____ after the bolus.
12-20 sec.
define Glomerulus
portion of the nephron responsible for filtering out unwanted substances from the blood
what is the primary clinical indication for non contrast cardiac CT?
coronary artery calcium (CAC) quantification for the assessment of atherosclerosis.
define spondylolithese
forward slipping of upper vertebra over the lower.
the liver receives 75% of its blood from the ____
portal vein.
where is cerebrospinal fluid produced?
choroid plexuses
what are the primary enhancement phases of the liver?
arterial
portal venous
equilibrium
what composes the circle of Willis?
anterior/posterior communicating arteries
anterior/posterior cerebral arteries
internal carotid artery
what are the retro-peritoneal structures?
duodenum
pancreas
adrenals
kidneys
ureters
bladder
what part of the cardiac cycle corresponds to the T-wave of an ECG?
complete cardiac diastole.
what is the difference between ionic and non ionic iodinated contrast?
non ionic contrast has a lower osmoality than ionic.
azotemia is ____ nitrogenous materials in the blood.
excessive
define Mean Transit Time (MTT)
time it takes for blood to pass through an area of brain tissue.
the duodenum is suspended from the diaphragm by the ____
ligament of Treitz
the kidneys are usually located where?
T12-L3
coronal imaging through the sinuses is typically performed with the plane of imaging ____ to the hard palate
perpendicular
the liver recieves 25% of its blood from the ____
hepatic artery
what are the stages of infection
incubation
prodromal
active
convalescence
the most common indication for CT gueded radiofrequency ablation is in treatment of neoplasms involving the ____
liver
the spinal cord tapers into the ____
conus medullaris
what imaging plane is spondylolithesis best demonstrated?
sagital
what is the average HU for an un-enhanced liver?
45-65 HU
define cortical-medullary phase
late arterial phase
temporal resolution is primarily affected by:
gantry rotation speed and number of slices per rotation.
what determines the number of HU on a specific image?
window width
what is a disadvantage of a small focal spot?
reduced heat capacity
define beam hardening artifacts
result from preferential absorption of low-energy x-rays, leaving only high intensity x-rays to strike the detector.
how is image quality evaluated?
spatial resolution
low-contrast resolution
temporal resolution
what is the primary advantage of filtering the x-ray beam?
reduces radiation dose to the patient
what is the difference in raw data and image data?
1.) raw data has not been made into and image
2.) raw data must be accessed to reformat images
3.) image data results once the computer has processed raw data and is the visualized image